British Journal of Pharmacology and Toxicology 4(2): 51-55, 2013
ISSN: 2044-2459; e-ISSN: 2044-2467
© Maxwell Scientific Organization, 2013
Submitted: November 19, 2012
Accepted: December 20, 2012
Published: April 25, 2013
Comparison between the Effect of Sildenafil versus Nifedipine in the Treatment
of Pulmonary Hypertention in Children
1, 3
Arwa Kh. A. Mohammed, 2Mohamed H. Meabed, 2Waleed M. El. Malah,
3
Mohamed E. Abdelrahim and 4Ahmed M. Goda
1
Teaching Hospital of Faculty of Medicine,
2
Pediatric Department, Faculty of Pharmacy,
3
Clinical Pharmacy Department, Faculty of Pharmacy,
4
Medicinal Chemistry Department, Faculty of Pharmacy, Beni Suef
University, Beni Suef, Egypt
Abstract: Pulmonary Hypertension (PH) is an increase of blood pressure in the pulmonary artery, pulmonary vein,
or pulmonary capillaries, together known as the lung vasculature, leading to shortness of breath, dizziness, fainting
and other symptoms, all of which are exacerbated by exertion. Pulmonary hypertension can be a severe disease with
a markedly decreased exercise tolerance and heart failure. The aim of this study is to evaluate the effect of sildenafil
versus nifedipine in the treatment of pulmonary hypertension in children. The study was carried out on 30
pulmonary hypertension patients (15 males and 15 females), 1 month to 10 years old and their weights ranged from
4 to 28 kg; from outpatient pediatric cardiology clinic at Bani suef university hospital; Patients were divided into
two equal groups. Group (A) received sildenafil in a dose of 0.1-1 mg/kg/dose every 8 h orally and group (B)
received nifedipine in adose of 0.5-3 mg/kg/dose every 8-12 h orally. Patients were treated and followed for 6
month. They were represented to full history taking, clinical examination, Echocardiographic examination in the
beginning and every 6 months of the study. there was an improvement in general health of children after therapy and
in respiratory rate, decreasing in pulmonary artery pressure in both groups but, the decrease in P.A.P in group A is
greater than group B and the improvement in H.R in group A is better than group B So, we concluded that usage of
sildenafil in children with pulmonary hypertension either primary or secondary is better and more effective than
usage of nifedipine.
Keywords: Fraction shortening, heart rate, nifedipine, pulmonary artery pressure, pulmonary hypertension,
sildenafil
be 10 mm Hg, the mean PA pressure was found to be
28.3+/-4.9 mm Hg in infants (Park, 2008).
Sildenafil produces acute and relatively selective
pulmonary vasodilatation and this seems to be
maintained long term (Erickson et al., 2002).
Sildenafil is a selective agent, which relaxes
pulmonary vascular smooth muscles. It is a potent
specific orally available Phosphodiestrase type 5
(PDE5) inhibitor. It facilitates Nitric Oxide (NO) cGMP
induced vasodilatation in the lungs by inhibiting the
degradation of cGMP and increasing its cellular levels
(Shyam and Bahanu, 2002).
PDE5 is found in high concentration in the lung.
The tissue specific distribution of PDE5 makes
sildenafil an attractive alternative or adjunct to current
therapies (Abrams et al., 2000). The terminal half life
of sildenafil is three to five hours (Eardley et al., 2000).
Previous studies have shown that the peak
hemodynamic effects of sildenafil occur at about 50
min after oral intake (Jackson et al., 1999).
INTRODUCTION
The right ventricle pumps blood returning from the
body into the pulmonary arteries to the lungs to receive
oxygen. The pressures in the lung arteries (pulmonary
arteries) are normally significantly lower than the
pressures in the systemic circulation. When pressure in
the pulmonary circulation becomes abnormally
elevated, it is referred to as pulmonary hypertension,
pulmonary artery hypertension, or PAH (Juliana and
Abbad, 2005).
Pulmonary hypertension can be classified into
primary (idiopathic) or secondary to pulmonary
parenchymal disease (such as meconium aspiration
syndrome, surfactant deficiency or alveolocapillary
dysplasia), severe pulmonary hypoplasia, polycythemia,
hypoglycemia, sepsis or maternal ingestion of
prostaglandin inhibitor (Adatia, 2002).
Pulmonary hypertension is known by using
tricuspid regurgitation jet velocity and the modified
Bernoulli equation, with right atrial pressure assumed to
Corresponding Author: Arwa Kh.A. Mohammed, Teaching Hospital of Faculty of Medicine, Beni Suef University, Beni Suef,
Egypt, Tel.: +201276151512
51
Br. J. Pharmacol. Toxicol., 4(2): 51-55, 2013
There are three general approaches using the
NO/cGMP pathway to treat PAH:
•
•
•
entry of calcium relaxes the muscles and dilates
(widens) the arteries (Nikol et al., 1997).
Increase supply of exogenous NO
Increase production of endogenous NO
Delay the metabolism of NO-induced synthesis of
cGMP (Kanki-Horimoto et al., 2006)
PATIENTS AND METHODS
A local hospital research ethics committee
approval was obtained for the patients study. Thirty
patients were included in the study (15 males and 15
females); their ages ranged from 1 month to 10 years
old and their weights ranged from 4 to 28 kg, they were
collected from outpatient pediatric cardiology clinic of
Beni Suef University Hospital with pulmonary
hypertension. The study was conducted during the
period of January to June/ 2011. An informed consent
was obtained from parents or legal guardians.
In the circulation, NO is bound by hemoglobin and
biologically inactivated, therefore, Inhaled Nitric Oxide
(INO) causes little or no systemic vasodilation or
hypotension, INO administrated by conventional or
high frequency ventilation in doses of 5-20 parts
permillion (ppm) causes pulmonary but not systemic
vasodilation and thus selectively decreases PVR (Van
Marter, 2008).
PDE-5 is selective for cGMP as substrate and
contains a noncatalytic high-affinity PDE-5 cGMP
binding site (with unknown function) similar to that of
PDE-2 and PDE-6. Convenient sources for purification
of the enzyme and testing of inhibitors are porcine or
human platelets. These inhibitors are often powerful
vasorelaxants, as PDE-5 also occurs in vascular smooth
muscle (Watanabe et al., 1998).
Several families of PDEs, the enzymes that
catalyze hydrolysis of the cyclic nucleoside
monophosphates 3'5'cAMP and 3'5'cGMP, have been
identified and characterized in recent years (Beavo,
1995). Sildenafil is a potent and selective inhibitor of
cGMP-specific PDE-5. This isoenzyme metabolizes
cGMP which is the second messenger of NO and a
principal mediator of smooth muscle relaxation and
vasodilatation. By inhibiting the hydrolytic breakdown
of cGMP, sildenafil prolongs the action of cGMP. This
results in augmented smooth muscle relaxation
(Reffelmann and Kloner, 2003).
The cAMP hydrolyzing PDE-3 and PDE-4 and the
cAMP, cGMP hydrolyzing isoform PDE-2, as well as
PDE-7 to PDE-11 are inhibited by sildenafil (Senzaki
et al., 2001).
Nifedipine belongs to a class of medications called
Calcium Channel Blockers (CCBs), dihydropyridine
derivative with a striking in vivo affinity for arterial
smooth muscle. When administrated to normal subject
or patient it produce dose- related decrease in peripheral
vascular resistance and systemic arterial pressure
(McAllister, 1986), that are used to treat angina (heart
pain), high blood pressure and abnormal heart rhythms
(Nikol et al., 1997).
Nifedipine and other dihydropyridines have the
greatest peripheral vasodilatory action with little effect
on cardiac automaticity, conduction, or contractility
(Kaplan, 1992).
Nifedipine works by blocking the flow of calcium
into the muscle cells surrounding the arteries that
supply blood to the heart (coronary arteries) as well as
other arteries of the body. Since the inflow of calcium
is what causes the muscle cells to contract, blocking the
1T
13T
1T
13T
Inclusion criteria: Patients diagnosed as pulmonary
hypertension.
Exclusion criteria: Patients with pulmonary
hypertension admitted to inpatient department with non
compromised cardiac condition.
All patients were evaluated by: Detailed history and
thorough clinical examination which includes Name,
age, sex, weight and Present history, with concentration
on shortness of breath with everyday activities,
Fatigue., Weakness and Syncope.
Patients were divided into two equal groups A and
B. Each group consisted of (15) patients:
•
•
Group (A): Represents patients who received
sildenafil in the dose of 0.1-1 mg/kg/dose every 8 h
orally.
Group (B): Represents patients who received
nifedipine in dose of 0.5-3 mg/kg/dose every 8-12 h
orally.
All these patients were subjected to:
1T
•
Thorough clinical examination every month for six
months, which includes:
Cardiovascular examination (Heart sounds, heart
rate murmur, perfusion and blood pressure)
Neurological examination (tone, reflexes, anterior
fontanel)
Respiratory
examination
{respiratory
rate,
retractions (intercostal, subcostal and suprasternal),
grunting, cyanosis, nasal flaring, breath sounds and
adventitious sounds}
Plain chest x-ray examination: It was done on the
start of the study to:
Diagnose any lung disease as grades of respiratory
distress syndrome, air leak.
Determine if there is any cardiomegally.
Determine the degree of lung inflation to adjust
mean airway pressure.
1T
1T
o
o
o
•
o
o
o
52
Br. J. Pharmacol. Toxicol., 4(2): 51-55, 2013
Table 1: Comparison between before and after treatment (in group A)
Before mean±S.D. After mean±S.D. p-value
Sig.
H.R
150.3±12.3
148.7±12.2
0.136
NS
R.R
48.3±12.3
29±7.4
0.001
HS
F.S
0.4±0.1
0.4±0.1
0.504
NS
P.A.P
53.8±11.1
31.2±6.1
0.001
HS
Echocardiography:
•
•
•
•
Vivid 3 pro (General electric) Duplex-pulsed
Doppler ultrasound machine with a 10 s MHZ
short focus probe and high pass filter at 50 HZ was
used.
Echocardiographic examination included M-mode,
2-D, Doppler and color flow mapping.
M-mode study was used for measurement of the
dimensions of cardiac chambers and vessels,
thickness of ventricular septum and free walls,
assessment of left ventricular systolic function.
Two-dimensional
echo
examinations
were
performed in the following transducer locations,
(parasternal, apical, subcostal and suprasternal
notch positions).
Table 2: Comparison between before and after treatment in group B
Before mean±S.D. After mean±S.D. p-value
Sig.
H.R
139.7±10.40
147.3±12.10
0.001
HS
R.R
45.7±13.90
38.0±13.20
0.001
HS
F.S
0.3±0.08
0.4±0.08
0.001
HS
P.A.P
55.1±11.50
48.8±11.80
0.030
S
groups before the beginning of study showed no
significant differences concerning Heart rate,
Respiratory rate, Ejection fraction, Fraction shortening
and Pulmonary artery pressure.
Means and SD of the collected data after therapy of
the two groups are shown in Table 1 and 2.
The study showed that the effect of sildenafil in
group A is better than the effect of nifedipine in group
B on pulmonary artery pressure, heart rate, Respiratory
rate and fraction shortening.
In pulmonary artery pressure, there was significant
decrease after the sildenafil treatment in group A
(p = 0.001) and there was significant decrease in group
B (p = 0.03) (Table 2).
In Fraction Shortening, there was an insignificant
difference after sildenafil treatment in group A
(p = 0.504) and there was significant decrease in group
B (p = 0.001).
After treatment, there was a significant difference
between the two groups regarding the decrease in
pulmonary artery pressure where, there was more
decrease in P.A.P of patients who received sildenafil
than the decrease in P.A.P of patients who received
nifedipine.
Also, After treatment, there was a significant
difference between A and B groups regarding the
clinical improvement in Heart rate and Respiratory rate
with p-value 0.038 and 0.029, respectively, where there
was better clinical improvement in sidenafil group than
nifedipine group, As nifedipine increase Heart rate
while sildenafil has no effect on heart rate.
However, there was no significant difference
between the two groups, after the six months therapy
regarding Fraction shortening with p-value 0.470
(Table 3).
It was performed initially before starting treatment to:
•
•
Establish the structural normality of the heart.
Estimate the ejection fraction and pulmonary artery
systolic pressure.
Statistical analysis: A two-way Analysis of Variance
(ANOVA) test was used to compare the effect of
Sildenafil verses nifedipine on clinical data and
Echocardiography examination using SPSS V15.0
(SPSS Inc., Chicago, IL).
Data was summarized as mean and Standard
Deviation (SD). p-value was calculated to compare
between the two groups, it is considered significant if
<0.05.
RESULTS
The study was conducted on 30 (15 females)
pulmonary hypertension patients, collected from
pediatric Cardiology Clinic at Beni Suef University
Hospital. The patients’ ages ranged from 1 month to 10
years old and their weights ranged from 4 to 28 kg,
Group A mean (S.D.) age is 34.1±35.7 Month. Group B
mean (S.D.) age is 25.3±31.0 Month.
In terms of age, weight and sex, all groups were
statistically homogenous. Also data analysis of the two
Table 3: Comparison between group A and group B regarding the following parameters
Group A mean±S.D.
Group B mean±S.D.
Age (month)
34.1±35.7
25.3±31.0
H.R
Before
150.3±12.3
139.7±10.4
After
148.7±12.2
147.3±12.1
R.R
Before
48.3±12.3
45.7±13.9
After
29.0±7.4
38.0±13.2
F.S
Before
0.4±0.1
0.3±0.08
After
0.4±0.1
0.4±0.08
P.A.P
Before
53.8±11.1
55.1±11.5
After
31.2±6.1
48.8±11.8
*: p<0.05; **: p<0.01; ***: p<0.0
53
p-value
0.481
0.506
0.038
0.582
0.029
0.592
0.470
0.762
0.001
Sig.
NS
NS
S
NS
S
NS
NS
NS
HS
Br. J. Pharmacol. Toxicol., 4(2): 51-55, 2013
decrease in pulmonary artery pressure in sildenafil
group than nifedipine group and there was no change in
heart rate in group A who received sildenafil while in
group B there was significant increase in heart rate after
usage of nifedipine.
DISCUSSION
The aim of the study was to evaluate the effect of
sildenafil versus nifedipine in the treatment of
pulmonary hypertension in children.
Clinical statistics of patients in all 6 months of the
study showed a significant decrease in P.A.P after
sildenafil therapy for 6 months in group A. These
results are similar to Leuchte et al. (2004), who
compared NO inhalation and oral sildenafil showed that
there was a decrease in pulmonary artery pressure and
pulmonary vascular resistance after usage of sildenafil.
Also, Gang et al. (2009), showed significant
decrease in pulmonary artery pressure after treatment
with sildenafil. While Mikhail et al. (2004), applied
sildenafil to 10 patients with pulmonary hypertension. It
was found that the cardiac function was improved.
Also, there was a significant decrease in P.A.P
after nifedipine therapy for 6 months in group B; these
results are similar to Schrader et al. (1992), who
applied nifedipine to 64 children with pulmonary
hypertension. It was found that mean of P.A.P
decreased after nifedipine. But, we found that the
decrease in P.A.P in sildenafil group was more evident
than nifedipine group, as p-value was 0.001 in group A
and 0.03 in group B.
In our study, Sildenafil showed no significant
effect on Heart rate in group A with p-value 0.136, our
results come in agreement with Baquero et al. (2006)
who found no change in heart rate before and after
treatment with sildenafil.
While, nifedipine showed significant increase in
heart rate in group B with p-value 0.001 as it reduced
the left to right shunt and increased the stroke volume.
Berisha et al. (1988) study revealed a similar results as
they found that, nifedipine significantly increased
systemic output and heart rate.
In comparing the effect of sildenafil versus
nifedipine on Heart rate, we found that there was
asignificant difference between the two groups with pvalue 0.038 as nifedipine increase H.R while sildenafil
has no effect on H.R.
In group A there was unnoticeable change in
Ejection fraction after sildenafil treatment for six
months and this lead to fraction shortening become
insignificant with p-value of 0.504, while in group B
there was a significant increase in fraction shortening
after nifedipine treatment with p-value 0.001, due to the
increase in ejection fraction and reduction in left
ventricular filling pressure. Our results comes in
agreement with the study done by Noori et al. (2007)
who found that sildenafil has no effect on fraction
shortening.
Finally the present study concluded that usage of
sildenafil in children with pulmonary hypertension
either primary or secondary is better, safer and more
effective than usage of nifedipine as there was more
CONCLUSION
Pulmonary hypertension patients in group A who
received Sildenafil in dose of 0.1-1 mg/kg/dose every
8 h orally showed more improvement regarding the
reduction in pulmonary artery pressure than the second
group which received nifedipine in dose of 0.5-3
mg/kg/dose every 8-12 h orally.
That usage of sildenafil in children with pulmonary
hypertension either primary or secondary is better, safer
and more effective than usage of nifedipine.
Further wider studies are needed to confirm the
results of the presented study.
ACKNOWLEDGMENT
We thank those patients that took part and the help
of all the staff involved with the delivery of care on the
pediatrics wards of Beni Suef University Hospital.
REFERENCES
Abrams, D., I. Schulze-Neick and A.G. Magee, 2000.
Sildenafil as a selective pulmonary vasodilator in
childhood primary pulmonary hypertension. Heart,
84: e4.
Adatia, I., 2002. Recent advances in pulmonary
vascular disease. Curr. Opin. Pediatr., 14: 292-7.
Baquero, H., A. Soliz, F. Neira, M.E. Venegas and
A. Sola, 2006. Oral sildenafil in infants with
persistent pulmonary hypertension of the newborn:
A pilot randomized blinded study. Pediatrics,
117: 1077-1083.
Beavo,
J.A.,
1995.
Cyclic
nucleotide
phosphodiesterases: Functional implications of
multiple isoforms. Physiol. Rev., 75: 725-748.
Berisha, S., A. Goda, A. Kastrati, A. Frasheri and
Y. Popa, 1988. Br. Heart J. Aug., 60(2): 149-155.
Eardley, L., P. Ellis, M. Bootell and M. Wulff, 2000.
Onset and duration of action of sildenafil citrate for
the treatment of erectile dysfunction. Br. J. Clin.
Pharmacol., 53: 61S-65S.
Erickson, S., J. Reyes, D. Bohn and I. Adatia, 2002.
Sildenafil (Viagra) in childhood and neonatal
pulmonary hypertension [Abstract]. J. Am. Coll.
Cardiol., 39(S2): 402A.
Gang, Q., Z. Yu-cai, H. Qi-wei, R. Qun-fang, G. Xiaohui and H. Min, 2009. Comparison study of using
sildenafil on persistent pulmonary hypertension of
the newborn. J. Clin. Pediatr., 27(8): 701-704.
Jackson, G., N. Benjamin, N. Jackson and M.J. Allen,
1999. Effects of sildenafil citrate on human
hemodynamic. Am. J. Cardiol., 83: 13C-20C.
54
Br. J. Pharmacol. Toxicol., 4(2): 51-55, 2013
Juliana, A.E. and F.C. Abbad, 2005. Severe persistent
pulmonary hypertension of the newborn in a setting
where limited resources exclude the use of inhaled
nitric oxide: Successful treatment with sildenafil.
Eur. J. Pediatr., 164: 626-629.
Kanki-Horimoto, S., H. Horimoto and S. Mieno, 2006.
Implantation of mesenchymal stem cells
overexpressing endothelial nitric oxide synthase
improves right ventricular impairments caused by
pulmonary hypertension. Circulation, 114(1):
1181-1185.
Kaplan, N.M., 1992. Systemic Hypertension,
Mechanisms and Diagnosis. In: Braunnald,
E. (Ed.), Heart Disease: A Text book of
Cardiovascular Medicine. 4th Edn., W.B. Saunders
Co., Philadelphia, pp: 817-864.
Leuchte, I.I., M. Schwaiblmair and R.A. Baumgartner,
2004. Hemodynamic response to sildenafil, nitric
oxide and ilioprost in primary pulmonary
hypertension [J]. Chest, 125(2): 580-586.
McAllister, R., 1986. Kinetics and dynamics of
nifedipine afier oral and sublingual doses. Am.
J. Med., 8: 12-5.
Mikhail, G.W., S.K. Prasad and W. Li, 2004. Clinical
and hemodynamic effects of sildenafil in
pulmonary hypertension acute and mid term effects
[J]. Eur. Heart J., 25(5): 431-436.
Nikol, S., T.Y. Huehns and B. Hofling, 1997. Novel
uses and potential for calcium antagonists in
revascularization. Eur. Heart J., 18(Suppl. A):
A105-A109.
Noori, S., P. Friedlich, P. Wong, A. Garingo and
I.N. Seri, 2007. Cardiovascular effects of sildenafil
in neonates and infants with congenital
diaphragmatic hernia and pulmonary hypertension.
Neonatology, 91(2): 92-100.
Park, M.K., 2008. Pulmonary Hypertension. In: Park,
M.K. (Ed.), Pediatric Cardiology for Practitioners.
5th Edn., Elsevier Inc., Mosby, Philadelphia, PA,
29: 121-485.
Reffelmann, T. and R.A. Kloner, 2003. Therpeutic
potential of phosphodiesterase 5 inhibition for
cardiovascular disease. Circulation, 108: 239-244.
Schrader, B.J., S. Inbar, L. Kaufmann, R.E. Vestal and
R. Stuart, 1992. Comparison of the effects of
adenosine
and
nifedipine
in
pulmonary
J.
Am.
Coll.
Cardiol.,
19(5):
1060hypertension.
1064.
Senzaki, H., C.J. Smith and G.J. Juang, 2001. Cardiac
phosphodiesterase 5 (cAMP-specific) modulates
beta adrenergic signaling in vivo and is down
regulated in heart failure. FASEB J., 15:
1718-1726.
Shyam, S.K. and D. Bahanu, 2002. Chronic oral
sildenafil
therapy
in
severe
pulmonary
hypertension. Indian Heart J., 54: 404-409.
Van Marter, L.J., 2008. Persistent Pulmonary
Hypertension of the Newborn. In: John, P.C.,
C.E. Eric and R.S. Ann (Eds.), Manual of Neonatal
Care. 6th Edn., Lippincott Williams and Wilkins,
Philadelphia, PA, 19106 USA, 24F: 358-364.
Watanabe, N., Y. Kabasawa, Y. Takase, M. Matsukura,
K. Miyazaki, H. Ishihara, K. Kodama and
H. Adachi, 1998. 4-Benzylamino-1 choro-6subsituted phthalazines: Synthesis and inhibitory
activity toward phosphodiesterase 5. J. Med.
Chem., 41: 3367-3372.
55